fn main() {
   //use std::collections::linked_list;
   let  immutable_varible:f64 = 10.0;
   let mut result_va:f64 = 11.0;
   let _ref1 = &result_va;
   result_va += immutable_varible;
   println!("the result is {}",result_va); 
   use ndarray::Array2;
   let mut array:Array2<f32> = Array2::zeros((3,3));
   array[[1,1]] = 1.0;
   println!("2d array:\n{}",array);
   use rand::Rng;
   let mut rng = rand::thread_rng();
   let n1:u8 = rng.gen();
   let n2:f64 = rng.gen();
   println!("random u8 :{}\n random f64:{}",n1,n2);
}
